Human Tongue Squamous Cell Carcinoma Research Articles

Antiangiogenic and antitumor effects of vascular endothelial growth factor small interfering RNA on Tca8113 human tongue squamous cell carcinoma xenografts in vivo

To examine the antiangiogenic and antitumor effects of vector-based small interfering RNA (siRNA) targeting vascular endothelial growth factor (VEGF) on human tongue squamous cell carcinoma xenografts in vivo. Tca8113 human tongue cancer nude mice xenograft model was established, and subsequently divided into four groups randomly (5/group). Two siRNA targeting VEGF constructed in eukaryotic expression vector (PU-VEGF-siRNA1, PU-VEGF-siRNA2) were injected intratumor and peritumor with lipofectamine 2000, respectively. No siRNA vector injected and non-injected tumors were used as experimented and negative controlled, respectively. Animals were injected one time every 3 days for a total of 10 times. Three days after the last injection, the weigh and volume of tumors, and intratumor microvessel density (MVD) were measured. The expression of VEGF in xenograft tumors was detected by reverse transcription polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. The cell apoptosis and cell cycle analysis of tumors were detected by Tunel and Flow cytometry, respectively. Compared to the experimental and negative controls, the percentage of cells in the G(1) phase increased (P < 0.05), the expression of VEGF on both mRNA and protein level, the tumor weigh and volume, and MVD decreased in the PU-VEGF-siRNA2 group (P < 0.05), and more apoptosis was induced (P < 0.01). But significant differences were not noted between PU-VEGF-siRNA1 group and two controls (P > 0.05). VEGF-siRNA can reduce VEGF expression, inhibit tumor growth and angiogenesis, and induce apoptosis in Tca8113 cell carcinoma in vivo. Different VEGF-siRNA may have different effect in vivo.

Measurement of annexin V uptake and lactadherin labeling for the quantification of apoptosis in adherent Tca8113 and ACC-2 cells

Phosphatidylserine (PS) exposure occurs during the cell death program and fluorescein-labeled lactadherin permits the detection of PS exposure earlier than annexin V in suspended cell lines. Adherent cell lines were studied for this apoptosis-associated phenomenon to determine if PS probing methods are reliable because specific membrane damage may occur during harvesting. Apoptosis was induced in the human tongue squamous carcinoma cell line (Tca8113) and the adenoid cystic carcinoma cell line (ACC-2) by arsenic trioxide. Cells were harvested with a modified procedure and labeled with lactadherin and/or annexin V. PS exposure was localized by confocal microscopy and apoptosis was quantified by flow cytometry. The detachment procedure without trypsinization did not induce cell damage. In competition binding experiments, phospholipid vesicles competed for more than 95 and 90% of lactadherin but only about 75 and 70% of annexin V binding to Tca8113 and ACC-2 cells. These data indicate that PS exposure occurs in three stages during the cell death program and that fluorescein-labeled lactadherin permitted the detection of early PS exposure. A similar pattern of PS exposure has been observed in two malignant cell lines with different adherence, suggesting that this pattern of PS exposure is common in adherent cells. Both lactadherin and annexin V could be used in adherent Tca8113 and ACC-2 cell lines when an appropriate harvesting procedure was used. Lactadherin is more sensitive than annexin V for the detection of PS exposure as the physical structure of PS in these blebs and condensed apoptotic cell surface may be more conducive to binding lactadherin than annexin V.

A new method to induce multi-drug resistance to carboplatin in a mouse model of human tongue squamous cell carcinoma

Multi-drug resistance (MDR) in human head and neck squamous cell carcinoma (HNSCC) constitutes a major obstacle to the effectiveness of chemotherapy. In previous studies, MDR was mainly induced in vitro. The authors report a novel in vivo method of inducing MDR in nude mice with xenotransplanted Tca8113 cells. Carboplatin, a chemotherapeutic agent used to treat HNSCC, was injected around the tumors for 10 weeks. A subsequent cell survival assay of dissociated tumor cells suggested that MDR had been induced successfully. Immunocytochemistry, reverse transcription polymerase chain reaction and Western blot analysis showed that the expression levels of MDR-related proteins, including topoisomerase II, MRP and glutathione transferase, were elevated in the induction group. The authors conclude that in vivo induction of MDR provides a useful method for establishing animal models of MDR.

Sulforaphane inhibited expression of hypoxia‐inducible factor‐1α in human tongue squamous cancer cells and prostate cancer cells

Previous studies show that a number of natural compounds from our diet have anticancer effects. Sulforaphane is the most characterized isothiocyanates (ITCs), which are identified in cruciferous vegetables. Sulforaphane is viewed as a conceptually promising agent in cancer prevention. Because of its ability to induce cancer cell apoptosis, it inhibits progression of benign tumors to malignant tumors and interrupts metastasis. However, the effect of sulforaphane on tongue cancer cell proliferation has not yet been reported, and the mechanisms that sulforaphane inhibits cancer development are still unclear. Hypoxia-inducible factor 1 (HIF-1) expression is associated with tumorigenesis and angiogenesis. It regulates the expression of many genes including vascular endothelial growth factor (VEGF), inducible nitric oxide synthase, and lactate dehydrogenase A. In our study, we investigated the effects of sulforaphane on expression of hypoxia-inducible factor-1alpha (HIF-1alpha), which was overexpressed in many human malignant tumors, human tongue squamous cell carcinoma and prostate cancer DU145 cells. Sulforaphane inhibited hypoxia induced expression of HIF-1alpha via inhibiting synthesis of HIF-1alpha. Sulforaphane was also found to inhibit hypoxia induced HIF-1alpha expression through activating JNK and ERK signaling pathways, but not AKT pathway. Inhibition of HIF-1alpha by sulforaphane resulted in decreasing expression of VEGF. Taken together, these results suggest that sulforaphane is an effective chemopreventive compound against tongue cancers and prostate cell angiogenesis in vitro, and that the HIF-1alpha target provides a new sight into the mechanisms of sulforaphane's inhibition against tumor cell proliferation.

Growth inhibition induced by transforming growth factor-β1 in human oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a world-wide health problem and its incidence accounts for 1.9-3.5% of all malignant tumors. Transforming growth factor beta/Smads (TGF-beta/Smads) signaling pathway plays an important role in oncogenesis, but its function and molecular mechanisms in OSCC remain unclear. Expression of transforming growth factor-beta receptor type II (TbetaRII) and Smad4 was studied by immunohistochemistry in 108 OSCC patients and 10 normal controls. Function and molecular mechanisms of TGF-beta/Smads signaling pathway was then investigated in two human tongue squamous carcinoma cell lines with high and low metastasis (Tb and Tca8113) by RT-PCR, Western Blot, immunofluorescence, cell growth curve and flow cytometry (FCM), respectively. TbetaRII and Smad4 were significantly down-regulated in tumor tissues (with or without lymph node metastasis) compared to normal oral epithelium tissues (P < 0.05). TGF-beta1 induced arrest of the cell cycle rather than cell death in Tca8113 and Tb cells, and this influence was mediated by the increasing the expression and changing the location of its downstream components of TGF-beta1/Smads signaling pathway. TGF-beta1 rapidly increased the expression of p15 and p21 in both Tca8113 and Tb cells. TGF-beta1 did not increase p27 expression in Tca8113 cells, but p27 expression was increased in Tb cells. These indicated that TGF-beta1 induced G(1) arrest of cell cycle through a different regulating pathway in Tb cells compared with Tca8113 cells. Thus, we conclude that TGF-beta/Smads signaling pathway play a important role on cell growth and metastasis potential in OSCC.

Protein microarray analysis of apoptosis-related protein expression following heat shock in human tongue squamous cell carcinomas containing different p53 phenotypes

Purpose: Hyperthermia is useful in the treatment of human head and neck cancers, because it is relatively easy to regulate temperatures when compared to tumors located in deep organs. In this study, attention was focused on p53 as a possible predictive indicator for the efficacy of hyperthermic cancer therapy.Methods: Two kinds of cell lines were used. These were derived from a human squamous cell carcinoma (SAS) and had identical genetic backgrounds except for their p53 gene status. It was previously reported that the heat sensitivity and frequency of apoptosis in wild-type p53 cells (SAS/neo) were clearly elevated when compared with mutated p53 cells (SAS/mp53). In order to study the expression of apoptosis related proteins after heat treatment, protein microarray analysis was used.Results: The expression of apoptosis inhibitory proteins such as Bcl-2, Bcl-xL, NF-κB, COX2, STAT3, IL-6, and IKKα/1 was seen to increase after heat treatment in SAS/mp53 cells, but not in SAS/neo cells.Conclusion: The result of these observations indicates that apoptosis inhibitory proteins (such as Bcl-2, Bcl-xL, IL-6, etc.) were highly induced in SAS/mp53 cells after heat treatment when compared to control SAS/neo cells.

The enamel matrix derivative (Emdogain ®) enhances human tongue carcinoma cells gelatinase production, migration and metastasis formation

Enamel matrix derivative Emdogain (EMD) is widely used in periodontal treatment to regenerate lost connective tissue and to improve the attachment of the teeth. Gelatinases (MMP-2 and -9) have an essential role in the promotion and progression of oral cancer growth and metastasis formation. We studied the effects of EMD on human tongue squamous cell carcinoma (HSC-3) cells in vitro and in vivo. In vitro, EMD (100 microg/ml and 200 microg/ml) remarkably induced the MMP-2 and -9 production from HSC-3 cells analysed by zymography and enzyme-linked immunosorbent assay. EMD also slightly induced the MMP-2 and -9 production from benign human mucosal keratinocytes (HMK). Furthermore, EMD clearly induced the transmigration of HSC-3 cells but had no effect on the HMK migration in transwell assays. The in vitro wound closure of HSC-3 cells was notably accelerated by EMD, whereas it had only minor effect on the wound closure of HMKs. The migration of both cell lines was inhibited by a selective cyclic anti-gelatinolytic peptide CTT-2. EMD had no effect on HSC-3 cell proliferation or apoptosis and only a limited effect on cell attachment to various extracellular matrix components. The in vivo mice experiment revealed that EMD substantially induced HSC-3 xenograft metastasis formation. Our results suggest that the use of EMD for patients with oral mucosal carcinomas or premalignant lesions should be carefully considered, possibly avoided.

Effect of hypoxia inducible factor-1 alpha on vascular endothelial growth factor expression in human tongue squamous carcinoma cells (Tca8113) under hypoxia

To investigate the effect of hypoxia inducible factor-1 alpha (HIF-1 alpha) on vascular endothelial growth factor (VEGF) expression in Tca8113 cells under hypoxia. The expression of the mRNA of HIF-1 alpha and VEGF in Tca8113 cells was examined by RT-PCR technique at different culture times (1/2 h, 1 h, 3 h, 6 h, 12 h, 24 h) under normoxic and hypoxic conditions. The expression of HIF-1 alpha under hypoxia showed the trend of increasing first and then decreasing, and was higher than that of the control (normoxic group) at 6h and 12 h (P < 0.05). The expression of VEGF under hypoxia was higher than that of the control group at 1/2 h, 1 h, 3 h, 12 h, 24 h (P < 0.05). The expression of hypoxia-induced VEGF mRNA increased with the increased expression of HIF-1 alpha mRNA in the cell lines tested at the initial stage of hypoxia. But no statistical significant association was observed between HIF-1 alpha and VEGF expression within 24 h under hypoxia (rs = 0.5750, P > .005). The increased expression of VEGF in Tca8113 cells might be mediated by multiple factors, including HIF-1 alpha.

Construction of targeting-Skp2 shRNA plasmids and observation of their inhibitory effect on Tca8113 cells

To construct the recombinant plasmids expressing Skp2 short hairpin RNA (shRNA) by pRNAT-U6.1/Neo plasmid vector and observe the effects of RNAi-mediated Skp2 gene silencing on Tca8113 cells. Five recombinant eukaryotic expression vectors were successfully constructed using pRNAT-U6.1/Neo plasmid vector separately. After they were transfected into Tca8113 cells with PEI, the interference effects no Skp2 and p27 were detected by RT-PCR and Western blot. The cell cycle of Tca8113 cells were tested by flow cytometry. The proliferation of Tca8113 cells were examined by MTT. In Skp2shRNA-2 and Skp2shRNA-3 vectors, the expression of Skp2 protein of Tca8113 cells was down-regulated and p27 protein up-regulated (P < 0.01). The cell number during G1/G 0 phases increased 22% (P < 0.01) and during G(2)/M and S phases the number decreased 10% and 12% (P < 0.01). The proliferation of Tca8113 cells slowed down and the cells number decreased (P < 0.01). Skp2shRNA-2 and Skp2shRNA-3 vectors of shRNA for Skp2 were successfully constructed. They could influence expression of Skp2 and p27 gene. Skp2 may be a promising target of gene therapy on human tongue squamous cell carcinoma.

In vitro evaluation of the anticancer effect of lactoferrin and tea polyphenol combination on oral carcinoma cells

We investigated the anticancer effects of green and black tea polyphenols alone and in combination with bovine milk lactoferrin (bLF) on human tongue squamous carcinoma (CAL-27) and normal human gingival fibroblast (HGF) cells. Both green (Polyphenon-E;P-E) and black tea polyphenols (Polyphenon-B;P-B) preferentially inhibit the growth of CAL-27 cells in a dose-dependent manner. Based on the IC(50) values, P-E was found to be more effective than P-B and the combination of P-E and bLF (1:2 ratio) exhibited synergistic inhibition of CAL-27 cells. Analysis of the mechanism revealed nuclear fragmentation and condensation with appearance of the A(o) peak indicative of apoptosis. Furthermore, tea polyphenols transduced the apoptosis signal via generation of reactive oxygen species and decrease in the Bcl-2/Bax ratio thereby inducing mitochondrial permeability transition with consequent activation of caspase-3. Overall, the potency of cytotoxic and apoptosis inducing effects of dietary agents on CAL-27 cells was in the order P-E and bLF combination (1:2 ratio)>P-E>P-B. These results suggest that a "designer" approach may be useful for oral cancer prevention strategies.

Using attenuated salmonella typhi as tumor targeting vector for MDR1 siRNA delivery: An experimental study

Objective: To investigate the feasibility of using attenuated Salmonella typhi as an in vivo delivery vector for multidrug-resistance gene (MDR1) small interference RNA (siRNA) in a mouse model bearing human tongue squamous cell cancer tumors. This technique may represent a novel and effective route for the in vivo administration of RNA interference therapy against malignant tumors. Methods: The cisplatin (DDP)-resistant human tongue squamous cell carcinoma cell line Tca8113/DDP, which highly expresses the MDR1 gene, was established by exposure to gradually increasing concentrations of cisplatin. MDR1 siRNA expression plasmids were constructed and transformed into attenuated Salmonella typhi strain SL7207. Tca8113/DDP cells were infected with recombinant salmonella and expression of the MDR1 gene encoded P-glycoprotein (P-gp) product was detected. Tca8113/DDP tumor-bearing nude mice were established by inoculation by gavage administration of recombinant salmonella and were simultaneously injected intraperitoneally with cisplatin. Tumor growth was observed. Results: Recombinant salmonella-bearing MDR1 siRNA expression plasmids can infect Tca8113/DDP cells in vitro and suppress P-gp expression and reverse DDP tolerance in Tca8113/DDP cells. Oral administration of recombinant salmonella in tumor-bearing nude mice can suppress tumor proliferation and enhance the therapeutic effect of DDP. Conclusion: Attenuated Salmonella typhi is expected to act as an in vivo targeting delivery vector for siRNA in tumor tissues.

Growth suppression induced by Notch1 activation involves Wnt—β‐catenin down‐regulation in human tongue carcinoma cells

Involvement of Notch1 signalling in several cancers is well known, but its role in human tongue squamous cell carcinoma, one of the most common carcinomas of the human oral cavity, remains poorly characterized. Our studies demonstrated that constitutively over-expressed active Notch1, via stable transfection of exogenous ICN (intracellular fragment of Notch), resulted in growth suppression of the human tongue cancer cell line Tca8113 in vitro and in vivo, accompanied by G(0)-G(1) cell cycle arrest and apoptosis. Moreover, down-regulation of beta-catenin protein expression was observed in Tca8113 cells stably expressing active Notch1. Activated Notch1 also led to dramatic increase in p21(WAF1/CIP1) and p53 expression with decreases in Skp2 (S-phase kinase-associated protein 2) and Bcl-2 (B-cell lymphocytic-leukaemia proto-oncogene 2) expression, which may participate in the induction of apoptosis and cell cycle arrest. Since the effects of the Notch1 pathway are cell-type specific and context-dependent in cell types where Notch1 has an anti-proliferative effect, down-regulation of Wnt/beta-catenin signalling may be one of the mechanisms which induces apoptosis and cell cycle arrest.

The cytotoxicity of combined paricalcitol, docetaxel and radiation in head and neck squamous cell carcinoma

15526 Background: Paricalcitol is a calcitriol analog used in the treatment of secondary hyperparathyroidism. It produces less hypercalcemia compared to calcitriol and has low clinical toxicity. We have shown previously that paricalcitol is antiproliferative in head and neck squamous cell carcinomas (HNSCC) in vitro. However, its interaction in combination with docetaxel and radiation has not been elucidated. The purpose of this study is to evaluate the combined effects of paricalcitol, docetaxel, and radiation in vitro in SCC-15 cells, a human tongue squamous cell carcinoma cell line. Methods: The cytotoxic effects were assessed using MTT assays. SCC 15 cells were plated, allowed to attach for 24 hours, and then treated with paricalcitol at 0, 12.5, 25, or 50 nM. After 24 hours, docetaxel at 0, 0.05, 0.15, or 0.3 nM was applied, followed in 24 hours by single treatment with radiation at 0, 2, 4, or 6 Gy. MTT assays were performed after incubation for 5 days. CalcuSyn analysis was used to determine if the interaction between paricalcitol, docetaxel, and radiation is synergistic, additive, or antagonistic. Results: Paricalcitol alone at 12.5, 24, and 50 nM produced growth inhibition of 30, 38, and 40%, respectively. Docetaxel alone at 0.05, 0.15, and 0.3 nM resulted in 33, 61, and 72% growth inhibition, respectively. Radiation at 2, 4, and 6 Gy produced 44, 57, and 62% inhibition, respectively. Sequential paricalcitol and docetaxel at the concentrations tested followed by 2 Gy radiation produced additive to synergistic cytotoxicity. Antagonism was seen with 4 Gy and all combinations of paricalcitol and docetaxel. Antagonism was also seen with 6 Gy and 0.15 or 0.3 nM of docetaxel. Conclusions: Sequential application of paricalcitol, docetaxel, and then radiation at moderate doses produced additive to synergistic cytotoxicity in SCC-15 cells. The results of this study provide support for further investigations of combined paricalcitol, docetaxel and radiation therapy in the treatment of head and neck cancers. [Table: see text]

Nanomanipulation of sections of human tongue squamous cell carcinoma by atomic force microscopy

To investigate the appropriate nanomanipulation of slides of human tongue squamous cell carcinoma tissue and cultured cells by atomic force microscopy (AFM), and develop methods to improve the resolution and contrast of AFM images. Human tongue squamous carcinoma cells of the line Tca8113 were cultured. Cell masses were isolated and collected, and sectioned. Then the white lead and silvery white sections were transferred on mica slides, dried. Eighty slides were used and divided into 2 groups to be immersed into hydrogen dioxide of the concentrations 20% and 30% for 0, 5, 10, 15, 20, 25, 30, and 40 min respectively. Samples of human tongue squamous carcinoma were collected from 15 cases. Every sample was divided into 2 halves. Half of every sample underwent routine paraffin preparation of slide and adhered onto glass, dissolving of paraffin with dimethylbenzene for 0, 10, 15, 30, 45, or 60 min; and half of the sample underwent routine preparation of slides for electron microscopy, the white lead and silvery white sections were transferred on mica slides, dried. The slides were observed by contact mode AFM in air. In the ultrathin sections the metastructure of the cell such as the cell membrane, nuclear membrane and nucleolus could be distinct from each other clearly. The profile of the cell and the nucleus inside could be revealed by AFM after the paraffin sections were treated in dimethylbenzene for 15-30 min. AFM manipulation could be achieved within nanometer range by precise modulation of scanning force, area, angle and so on. The appropriate needle point should contain elastic coefficient > 5.0 N/m. The force exerted on the needle point should be within the range 50-300 nN. After location the scanning direction should be within the range of 20 nm-1 microm. A series of modified techniques of preparing and treating AFM samples, such as adhering the sections onto mica slide, dissolving of epoxy resin by hydrogen dioxide and removal of paraffin by dimethylbenzene, were developed, thus realizing high resolving power AFM imaging, especially for nuclear membrane, and nucleolus, and providing a base of AFM location, dissection, isolation and obtainment at nanometer scale.

Human tongue carcinoma growth is inhibited by selective antigelatinolytic peptides

Matrix metalloproteinases (MMP-2 and MMP-9, or gelatinases) are involved in tongue SCC invasion, metastasis and angiogenesis. We have recently shown that a novel and selective hydrophobic cyclic CTTHWGFTLC (CTT1) peptide is inhibitor for MMP-2 and MMP-9 (Koivunen et al., Nat Biotechnol 1999; 17:768-74). In this study, we demonstrate that both the new hydrophilic derivate GRENYHGCTTHWGFTLC (CTT2) peptide and the CTT1 peptide inhibited specifically the human tongue squamous cell carcinoma (HSC-3) cell-derived gelatinolytic activity and in vitro invasion and migration of these cells (p < or = 0.049). In situ zymography revealed that both peptides also inhibited clearly almost all of the gelatinolytic activity present in the human tongue SCC tissue sections, indicating that MMP-2 and MMP-9 are the major gelatinases detected in the tongue carcinomas. However, CTT2 did not inhibit the type I collagen degradation by human collagenases (MMP-1, MMP-8 and MMP-13). Furthermore, CTT2 reduced the blood vessel density (p < or = 0.043) and clearly improved the survival of the mice bearing human tongue carcinoma xenografts (p < or = 0.012). Overall, we suggest that CTT1 and CTT2 peptides being selective gelatinase inhibitors with significant anti-tumor properties could be useful to diminish the invasion and angiogenesis of human tongue carcinomas characterized by enhanced gelatinolytic activity in tumors.

Resveratrol inhibits hypoxia-induced accumulation of hypoxia-inducible factor-1α and VEGF expression in human tongue squamous cell carcinoma and hepatoma cells

Hypoxia-inducible factor-1alpha (HIF-1alpha) is overexpressed in many human tumors and their metastases, and is closely associated with a more aggressive tumor phenotype. In this study, we investigated the effect of resveratrol, a natural product commonly found in grapes and various other fruits, on hypoxia-induced HIF-1alpha protein accumulation and vascular endothelial growth factor (VEGF) expression in human tongue squamous cell carcinomas and hepatoma cells. Our results showed that resveratrol significantly inhibited both basal level and hypoxia-induced HIF-1alpha protein accumulation in cancer cells, but did not affect HIF-1alpha mRNA levels. Pretreatment of cells with resveratrol significantly reduced hypoxia-induced VEGF promoter activities and VEGF expression at both mRNA and protein levels. The mechanism of resveratrol inhibition of hypoxia-induced HIF-1alpha accumulation seems to involve a gradually shortened half-life of HIF-1alpha protein caused by an enhanced protein degradation through the 26S proteasome system. In addition, resveratrol remarkably inhibited hypoxia-mediated activation of extracellular signal-regulated kinase 1/2 and Akt, leading to a marked decrease in hypoxia-induced HIF-1alpha protein accumulation and VEGF transcriptional activation. Functionally, we observed that resveratrol also significantly inhibited the hypoxia-stimulated invasiveness of cancer cells. These data suggested that HIF-1alpha/VEGF could be a promising drug target for resveratrol in the development of an effective chemopreventive and anticancer therapy in human cancers.

Effects of ATRA, acitretin and tazarotene on growth and apoptosis of Tca8113 cells

To investigate the effects of ATRA, acitretin and tazarotene on the growth and apoptosis of human tongue squamous cell carcinoma cell line Tca8113. The effect of retinoids on growth of Tca8113 cells in vitro was examined by MTT assay and Trypan blue exclusion assay. Cell cycle analysis, early apoptosis analysis with double staining with Annexin V-FITC and PI, and active caspase-3 analysis with the staining of FITC-conjugated monoclonal rabbit anti-active caspase-3 antibody were made by flow cytometer. Streptavidin-biotin complex (SABC) immunocytochemical assays were employed for the detections of Bax/Bcl-2 proteins expressions. Our results showed that the retinoids inhibited growth of Tca8113 cells in a dose- and time-dependent manner with maximal inhibition 24 h after treatment of 10(-5) mol/L. 10(-5) mol/L retinoids altered cell cycle distribution of Tca8113 cells, revealing an increase in G0/G1-phase population, a decrease in S-phase population and the inhibition of G1/S switching. 10(-5) mol/L retinoids significantly induced apoptosis of Tca8113 cells (all P < 0.05), elevated the cells population with detectable active caspase-3 (P < 0.05 for all), increased the number of cells forming Bax and decreased the number of cells forming Bcl-2 significantly (all P < 0.05). Acitretin played a most prominent role among the retinoids. It is concluded that the inhibition of cell cycle progress of Tca8113 cells by ATRA, acitretin and tazarotene is one of the possible mechanisms for proliferation arrest of Tca8113 cells elicited by the retinoids. The retinoids mediate apoptosis in Tca8113 cells that may be caspase-dependent through mitochondria pathway. High concentration retinoids inhibit growth of Tca8113 cells in vitro by interfering with proliferation and inducing apoptosis of cells. Acitretin may be an alternative medicine for the prevention and treatment of tongue squamous cell carcinoma.

Synergistic down-regulation of telomerase by all-trans retinoic acid and antisense oligonucleotide in oral squamous cell carcinoma cell line (Tca8113)

Human telomerase, activated in about 90% of cancers, is mainly composed of hTR, hTERT and TP1. The exposed RNA template of hTR is an ideal target for antisense oligonucleotides (As-ODN); while recent findings indicate all-trans retinoid acid (ATRA) could effectively inhibit the expression of catalytic subunit-hTERT. The aim of this study was to investigate the effect of ATRA and As-ODN in oral squamous cell carcinoma and whether telomerase activity could be synergistically inhibited by them and thus therapeutically exploited in the future. As-ODN-hTR was transfected into human tongue squamous cell carcinoma cell line (Tca8113) with or without ATRA. Telomerase activity was examined by PCR-Elisa; viability was compared with growth curve; apoptotic rate was analyzed by Annexin V/PI double staining and hTERT expression was tested with western blot. Tca8113 cells displayed significant growth inhibition during the 9-day exposure to ATRA/As-ODN, especially to a combination of As-ODN-hTR and 5muM ATRA, correlating with the inhibition of telomerase expression. The relative telomerase activity was inhibited during treated with As-ODN-hTR alone, ATRA alone, or a combination of them. While without ATRA, the effect of As-ODN would disappear at 96h after transfection. As-ODN-hTR alone or combined with ATRA also significantly increase the apoptotic rate. Our findings provided direct evidence, in oral squamous cell carcinoma, As-ODN-hTR and ATRA could synergistically inhibit telomerase activity and telomerase protein in human tongue squamous cell carcinoma cells, which correlated with the induction of growth arrest.

Tumor Growth, Local Invasion, Micrometastasis, and Lymph Node Metastasis of Oral Squamous Cell Carcinoma Visualized in Live Tissue by Green Fluorescent Protein Expression

We report the in vitro establishment of a highly stable green fluorescent protein (GFP)-expressing transfectant of a highly-invasive human tongue squamous cell carcinoma (HTSCC) cell line, SAS-H1. The fluorescent cells permitted the visualization of tumor growth, local invasion, micrometastasis and cervical lymph node metastasis after submucosal injection into the tongues of nude mice. SAS-H1 cells were transfected with the pEGFP-N1 expression vector containing the GFP and neomycin resistance genes. Stable SAS-H1 clones expressing high levels of GFP were selected stepwise in vitro in levels of geneticin (G418) of up to 3,500 μg/ml. Subsequent early stages of local invasion and micrometastasis were visualized by GFP fluorescence in a primary tumor of the tongue. Furthermore, lymph node metastasis was confirmed for all of the orthotopic transplants in mice. However, no distant metastases, including those of lung and liver, were observed. Thus, this model should be useful for studying the metastatic process and for evaluating anti-metastasis agents in pre-clinical trials.

N-Acetylglucosaminyltransferase V Expression is Implicated in Malignant Phenotype of Human Tongue Squamous Cell Carcinoma.

The expression of GnT-V has been shown to correlate with tumor invasion, metastasis and poor prognosis in several tumors. We examined the expression of glycosyltransferases, N- acetylglucosaminyltransferase V (GnT-V) in 40 cases of human tongue squamous cell carcinoma (SCC) and its relationship to clinicopathological characteristics. Twenty-six of the 40 cases of SCC showed positive expression of GnT-V in cytoplasm of tumor cells by imunohistochemistry, whereas none of the 4 premalignant lesions showed positive signals for GnT-V. High expression of GnT-V was positively correlated with big tumor size (T category), infiltrative invasion pattern (vs. expansive), high histological malignancy (differentiation), and cervical lymph node metastasis. Furthermore, in the early clinical stage of SCC, the subsequent metastatic rate was significantly higher in SCCs that were GnT-V positive than in SCCs that were GnT-V negaive. All SCC cases examined showed increased GnT-V mRNA levels in comparison to normal tongue tissues by real-time PCR. Contrastively, GnT-V expression was not enhanced in premalignant lesions. These findings suggest that GnT-V expression is closely correlated with tongue SCC progression and the malignant phenotype.